1. Field of the Invention
The present invention relates to a photoelectric conversion apparatus for detecting focus, which performs phase difference detection auto-focusing.
2. Description of the Related Art
Conventionally, for photoelectric conversion apparatuses for auto-focusing (AF) (auto-focus (AF) sensors), it has been proposed to switch effective regions in a sensor depending on the light-projection unit of the light source for ranging according to the scene to be shot, as indicated in Japanese Patent Application Laid-Open No. 2002-214516. Japanese Patent Application Laid-Open No. 2002-214516 describes that, for example, in a first ranging mode, focusing is performed by ranging one ranging point when light is emitted, and in a second ranging mode, focusing is performed by ranging seven ranging points when no light is emitted. In the art, various types of AF modes are employed to deal with scenes for which ranging is difficult to perform, and the effective regions in the sensor array can properly be switched, and thus, a correct ranging result can always be obtained, suppressing occurrence of a miss-focusing shooting result.
Also, in recent years, there has been an increasing demand for providing an increased number of auto-focus ranging points, an area-type phase difference detection AF sensor, which is regarded as being advantageous for providing an increased number of ranging points is disclosed in Japanese Patent Application Laid-Open No. 2007-65324. Conventional area-type AF sensors, as disclosed in Japanese Patent Application Laid-Open Nos. H09-200614 and H09-200629, image signals from effective sensor elements are transferred to and retained in frame memories connected one by one to the sensor elements. Furthermore, according to Japanese Patent Application Laid-Open No. H11-191867, when adjacent ranging regions are projected on the surface of the sensor, the regions partially overlap in the column direction owing to the effect of the optical system of the AF unit.
While the abovementioned area-type phase difference detection AF sensor is used for high-speed and high-precision auto-focusing of multiple ranging points in a wide area, it has a problem in a cost increase caused by a chip-area increase.